Many types of motor vehicles have been developed to improve the fuel efficiency of motor vehicles. In general, an improvement in fuel economy is accomplished through severe down-sizing of the internal combustion engine of the vehicle. This permits the vehicle to travel greater distances on reduced amount of fuel. This, however, results in severely slow acceleration which is unacceptable to the buying public.
Various solutions have been proposed to solve this problem. One solution involves use of two or more internal combustion engines in the vehicle. One engine is down-sized and is used to permit the vehicle to travel greater distances on reduced amount of fuel. The additional engine(s) provides more power for faster acceleration, hill-climbing, etc.
Examples of vehicles involving two or more internal combustion engines are found in the following U.S. Pat. Nos. 6,179,078; 7,270,030; 7,080,622; 8,561,744 and 7,410,021. Unlike the present invention, none of them discloses the use of an electric motor to supply additional power for traction and to provide means for regenerative braking to recharge batteries.
Another solution involves the use of one or more electric motors adapted to augment the output of the internal combustion engines when more power is needed. These are known as hybrid vehicles. Hybrid vehicles tend to be more expensive than a non-hybrid vehicle of comparable size and power because of the high cost of the required batteries and associated electrical components. They also tend to have poorer acceleration and mechanical performance, for the same reason. They do have an advantage over non-hybrid vehicles by having the ability to recover energy from the kinetic energy of the moving vehicle through regenerative braking.
Examples of hybrid vehicles involving one internal combustion engine and one electric motor are found in the following U.S. Pat. Nos. 5,513,719; 5,788,003; 6,044,922; 6,209,672; 6,328,671; 6,668,954; 6,706,789; 6,712,165; 6,958,549; 6,995,480; 7,004,273; and 7,028,796.
Hybrid vehicles involving a single internal combustion engine in association with two or more electric motors are disclosed in the following U.S. Pat. Nos. 5,343,971; 6,717,281; 6,856,025; 6,959,237; 6,962,224; 6,965,173; and 7,044,255.
None of these patents disclose a vehicle having more than one internal combustion engine, whereas the vehicle of the present invention has a plurality of internal combustion engines in addition to an electric motor to propel the vehicle.
U.S. Pat. No. 7,647,994 to Belloso discloses a vehicle having two internal combustion engines and an electric motor, however, only the first internal combustion engine is coupled to the speed change transmission. The second internal combustion engine is coupled to a generator and it is used simply to recharge the hybrid battery. This is unlike the present invention wherein both the first and second internal combustion engines are coupled to the speed change transmission and directly propel the vehicle.
U.S. Pat. No. 7,641,584 to Belloso discloses a vehicle with primary cruiser engine and auxiliary accelerator engine. The first five embodiments do not involve the use of an electric motor to help propel the vehicle and are, therefore, unlike the present invention. Although the fifth and sixth alternative embodiments involve the use of two internal combustion engines and an electric motor, they differ from the present invention because the secondary (“accelerator”) engine in each case is used only to drive the electric generator to replenish the charge of the battery and they are not coupled to the speed change transmission, whereas in the present invention both the primary engine and the secondary engine are mechanically coupled to the speed change transmission and directly propel the vehicle.
U.S. Pat. No. 7,325,638 to Belloso discloses a motor vehicle with a primary engine for acceleration and a secondary engine augmented by an electric motor for cruising. Unlike the present invention wherein both the primary and secondary engines are coupled to the speed change transmission, the secondary engine of U.S. Pat. No. 7,325,638 is not coupled to the speed change transmission. Instead, it is directly coupled to the differential, completely bypassing the speed change transmission. Power from the secondary engine, therefore, does not benefit from the torque multiplication afforded by the speed change transmission during acceleration.
It is accordingly an objective of this invention to provide a vehicle capable of traveling at cruising speed for long distances with maximum fuel economy through maximal down-sizing of the engine specifically designated for cruising. Maximal down-sizing of the primary (“cruiser”) engine is made possible in this invention because its power is not needed for acceleration, hill-climbing, etc., since there is a designated secondary (“accelerator”) engine to supply the additional power.
It is another objective of this invention to provide a vehicle having sufficient power for quick acceleration and good hill-climbing abilities through the use of a sufficiently powerful secondary engine releasably coupled to the speed change transmission.
It is an additional objective of this invention to further improve the acceleration of the vehicle through use of an electric motor-generator powered by a rechargeable battery to provide additional power for acceleration.
It is still an additional objective of this invention to further improve fuel economy by recharging the battery through regenerative braking with the motor-generator in generator mode.
It is a still further objective of this invention to provide a fuel-efficient hybrid vehicle having less expensive lower capacity batteries and electric motors.
These objectives and other objectives and advantages of the invention will be apparent from the following description.